He started his career with Sporting, making his debut with the first team in 2011 before signing with Liverpool two years later. He spent three seasons in the English Championship with Reading after joining in January 2017, and also competed professionally in Spain and France.

In only his fourth official appearance for Sporting, on 16 February 2013 at Gil Vicente FC, Ilori again played the entire match, and helped to a 3–2 success by scoring the former's second goal in the sixth minute.[6]

On 2 September 2013, Ilori was signed by Liverpool for an undisclosed fee, reported to be around £7 million.[7][8] It was also announced that The Football Association were in talks with the player for him to switch nationality and represent England internationally.[3][9]

Fellow Premier League club Aston Villa signed Ilori on a season-long loan deal on 1 September 2015.[15] On 7 January 2016, the move was cancelled and he returned to Liverpool, making his first competitive appearance with the first team the following day by starting the FA Cup third round match against Exeter City, which ended with a 2–2 draw at St James Park.[16]